Candles are often made from petroleum based wax such as paraffin wax. Prior to the development of petroleum based waxes, candles were typically made from animal fats such as tallow, etc.
Candles made from either of these two materials are disadvantageous in that they produce an undesirable amount of soot or smoke, darkening ceilings, curtains and other surfaces. Petroleum based candles are further disadvantageous in that they are from a non-renewable source, and animal based candles are objectionable to some people (because they are made from a source that is inefficiently high on the food chain, amongst other reasons).
U.S. Pat. No. 1,954,659, issued to Will on Aug. 6, 1934, for a Candle and Method of Making Same, teaches a candle that includes “50 or more vegetable oil combined with paraffin wax, stearic acid, beeswax or other waxes, if the vegetable oil, such as rapeseed oil is first hydropenated.”The goal of the Will patent is to process vegetable oil in such a manner as to cause it to change from a liquid to a solid. The type of oil used by Will (e.g., high erucic-content rapeseed) and his “hydrogenation” method achieved a solidification, or “hardening,” of the oil. Nonetheless, Will's use of the word “hydrogeration” has a meaning different from hydrogenation as used in the present invention. For example, circa 1930 hydrogenation was carried out using a hydrogenation catalyst that favored both (1) hydrogenation of unsaturated triglyceride fatty acid molecules and (2) isomerization of cis (“Z”) fatty acid isomers to trans (“E”) fatty acid isomers. Both (1) and (2) result in an increased melting point, and thus the desired “hardening” of the oil is achieved without fully hydrogenating the unsaturated triglycerides. This in turn results in a candle that is sufficiently hard for its intended purposes, but that creates an undesirable amount of smoke or soot due to unsaturated triglycerides.
By circa 1930 standards, it is estimated that the Iodine Value (IV) for hydrogenated (“hardened”) rapeseed oil would have been 15 or greater because it is very high in erucic acid (approximately 20% or higher C22 mono-unsaturated fatty acid content). It should be noted that IV measurements are known in the art and IV is a measure of the degree of unsaturation of a fatty acid (whether free or as part of a triglyceride). More information is provided below concerning IVs.
With respect to lower-soot, loser-smoke candles, beeswax has been used to make candles that were purported to be less sooty and smoky than paraffin candles. The process of obtaining beeswax, however, is complicated and time consuming and, therefore, renders beeswax candles disadvantageously expensive. Additionally, modern testing of beeswax candles has shown that while they may have a lower propensity to soot than paraffin candles, it is still undesirably high.